• Phylum Echinoderms (Invertebrates)
• Phylum Chordata (mostly Vertebrates)
  • Independent evolution of each group

• Deuterostome = Developmental similarities
  • radial cleavage
  • anus from blastopore

• HOWEVER: other basal animal phyla share some of these traits
  • Deuterostomes now defined by DNA

• Protostome = First Mouth

• Deuterostome = Second Mouth

• Two groups differ by embryonic development

• Translates to ‘Spiny Skin’
  • sea stars and urchins
  • slow moving and marine
  • adult = radial, larval = bilateral

• Thin epidermis covered in hard plates
  • often with bumps or spines

• Translates to ‘Spiny Skin’
  • sea stars and urchins
  • slow moving and marine
  • adult = radial, larval = bilateral

• Thin epidermis covered in hard plates
  • often with bumps or spines

• Possess a unique water vascular system
  • flexible hydraulic canals = tube feet

• All chordates share 4 traits
• Some only in embryo stages

1. Notochord
2. Dorsal, hollow nerve cord
3. Pharyngeal slits
4. Muscular, Post-anal tail

• 2 invertebrates groups that are more related to vertebrates
  • Cephlachordata (lancelets)
  • Urochordates (tunicates)

• Possess skeletal and nervous systems
  • simple to complex backbones
  • lots of unique genes (eg. HOX)

• Derived trait = neural crest
  • special cells near neural tube in embryo
  • give rise to many vertebrate traits
  • e.g.. teeth, skull cartilage, etc

• Evolved while predators where developing
  • Cambrian period
  • Ocean origins (first 150 mya)

• Vertebrate: series of bones that make up the vertebral column
  • 57,000 species

• Vertebrates with limbs colonized land 365 mya

1. Amphibians
2. Reptiles (w/ birds)
3. Mammals

• Only members of vertebrates without jaws
  • sister group of jawless fish

• Have rudimentary backbones
  • more cartilage than bone

• Hagfish escape by releasing slime
  • researched to stop bleeding in surgery

• Only members of vertebrates without jaws
  • sister group of jawless fish

• Have rudimentary backbones
  • more cartilage than bone

• Hagfish escape by releasing slime
  • researched to stop bleeding in surgery

• Many Lamprey are parasitic on fish
  • invaded Great Lakes
  • native to Chesapeake Bay

• ‘Cartilage fishes’: skeletons mostly cartilage
  • often with calcium
  • originated 400 mya

• Streamlined body for swift swimming
  • poor maneuverability
  • near constant motion

• Birth via eggs or young develop inside mother

• Modern species diversity shrinking

• Phylogeny: large new vertebrate group with bony endoskeletion
  • fishes = aquatic groups

Add lungs/lung derivatives to phylogeny

• Important derived traits for fishes:
  • operculum:
  • swim bladder:

• Ray-finned: bony rays that support fins
  • trout, sea horses, eels

• Lobe-finned: rod-shaped bone surrounded by muscle in fins
  • lungfish, Coelacanths, earliest tetrapods

• A fish has a density of about 1.076
  • freshwater has a density of 1.0
  • saltwater has a density of 1.026

• Bone is nearly twice as dense as cartilage

• Swimming is energy expensive
  • resting on the bottom may not be practical

• Evolution of the swim bladder set fish free